Ringleader Abdulla Ahmed Ali, 28, of east London, was convicted of conspiring to detonate bombs disguised as soft drinks by Woolwich Crown Court.

Islamic extremists Tanvir Hussain, 28 and Asaad Sarwar, 29, were also found guilty of the same charge.

The attacks were planned on flights from London to major north American cities and would have exceeded the carnage of the September 11 attacks, with thousands killed in the air and on the ground.

The plot, planned on flights between January 1 and August 11, 2006, led to the airport restrictions on liquids that caused travel chaos.

Ali, Hussain and Sarwar were convicted of conspiracy to murder in the first trial but were retried, along with five other men, for the planned attacks after the first jury failed to reach verdicts on those charges.

But today a second jury decided the terror plot did exist.

Other members of the terrorist cell - Ibrahim Savant, 28, of Stoke Newington, Arafat Waheed Khan, 28, of Walthamstow, Waheed Zaman, 25, of Walthamstow - were today found not guilty of the airliner plot.

The jury failed to reach a verdict on Umar Islam, 31, of of the airliner plot but he was convicted of conspiracy to murder.

Donald Stewart-Whyte, 23, of High Wycombe, was also found not guilty of both conspiracy to murder on aircraft and conspiracy to murder.

Ali, who was the leader of the east London al Qaida-inspired terror cell, was responsible for the most complex and daring British-based terrorist conspiracy in modern times.

Counter terrorist police, the security services and prosecutors spent more than £35 million foiling the plot and bringing him to justice.

The guilty verdict will come as an enormous relief for Government ministers who endured heavy criticism for introducing the draconian luggage restrictions.

Today Home Secretary Alan Johnson said: “I am pleased that the jury has recognised that there was a plot to bomb transatlantic flights and that three people have been convicted of that plot.

“This case reaffirms that we face a real and serious threat from terrorism. This was a particularly complex and daring plot which would have led to a terrible attack resulting in major loss of life.

“The police, security services and CPS have done an excellent job in bringing these people to justice.

“This was the largest ever counter terrorism operation in the UK and I cannot thank enough those involved for their professionalism and dedication in thwarting this attack and saving thousands of lives.”

It will also be seen as a vindication of the decision to retry Ali after he was found guilty of conspiracy to cause explosions last September. The previous jury failed to reach verdicts on the airline plot.

British-born Ali was inspired by the July 7 bombers and Osama bin Laden and considered taking his baby son on his suicide mission.

He planned to smuggle home-made bombs disguised as soft drinks on to passenger jets run by United Airlines, American Airlines and Air Canada.

The hydrogen peroxide devices would have been assembled and detonated in mid-air by a team of suicide bombers.

Ali singled out seven flights to San Francisco, Toronto, Montreal, Washington, New York and Chicago that departed within two-and-a-half hours of each other.

Authorities on both sides of the Atlantic would have been left powerless to stop the destruction once the first bomb exploded.

Police said the plot was drawn up in Pakistan with detailed instructions passed to Ali during frequent trips to its lawless border with Afghanistan.

They believe a mystery al Qaida bombmaker was responsible for the ingenious liquid bomb design, concealed within 500ml Oasis or Lucozade bottles.

Surveillance teams watched Ali on his return to Britain as he assembled his terror cell, gathered materials and identified targets.

Undercover officers looked on as the unemployed former shop worker used cash to purchase a £138,000 second-floor flat in Forest Road, Walthamstow.

They planted a secret bug that revealed it was converted into a bomb factory where Ali met others to construct the bombs.

The flat was also used as a location for Ali and others to record suicide videos threatening further attacks against the West.

In his video Ali warned the British public to expect “floods of martyr operations” that would leave body parts scattered in the streets.

Ali was watched as he used public phone boxes, mobile phones and anonymous email accounts to keep in touch with mystery terrorist controllers in Pakistan.

On his arrest, he was found to be carrying an elaborate and damning blueprint for the plot scrawled in a battered pocket diary.

Airport security arrangements and details of flights, including the seven highlighted services, were discovered on a computer memory stick in another pocket.